Surgical stapling is commonly used to close surgical incisions. Surgical stapling benefits the patient by reducing the amount of time the patient is under anesthesia. It also benefits physicians by eliminating much of the time and energy that was previously spent suturing surgical incisions with traditional needle and silk, polymer, or gut thread. As a result, surgical stapling has become the procedure of choice for incision closure, especially when confronting large incisions or wounds.
Conventional staples used in surgical stapling initially were formed from stainless steel. However, properly deploying stainless steel staples proved difficult because of the substantial amount of force required to deform stainless steel staples into a closed position. A great deal of innovation was thus directed to surgical staplers. Despite this effort, surgical staplers continue to suffer from one or more of the following drawbacks. Surgical staplers are relatively heavy and bulky; they are expensive because of their complex inner workings; they often obstruct the target location for the staple; and each stapler is intended for a narrow range of procedures.
As a result of their unique characteristics, shape memory alloys (“SMAs”) have become viable alternatives to stainless steel. Shape memory materials are capable of returning to a previously defined shape and size when subjected to an appropriate thermal treatment. For example, a shape memory material having an initial configuration above a first transformation temperature may be cooled to below a second transformation temperature and then deformed to take on a different configuration. Then, upon heating above the first transformation temperature, the material may “remember” and spontaneously recover the initial configuration. The basis for this behavior is a substantially reversible phase transformation that occurs when the temperature of the material moves below and above its transformation temperatures. Using surgical staples formed from SMAs may reduce or eliminate the need to apply a substantial deforming force to fasten the staples. A shape memory surgical staple is described in U.S. Pat. No. 4,485,816, to Krumme, entitled “SHAPE-MEMORY SURGICAL STAPLE APPARATUS AND METHOD FOR USE IN SURGICAL STAPLING,” which is incorporated herein by reference in its entirety.
Despite the significant advance of using SMA surgical staples instead of stainless steel surgical staples, the staplers used to deliver SMA surgical staples suffer from one or more of the following drawbacks. First, such staplers are unsuitable for use in endoscopic procedures. That is, such staplers are not deliverable through the working channel of an endoscope. Accordingly, endoscopically (or laparascopically) created incisions cannot be closed with traditional SMA staplers. Second, these staplers require that both tines of a staple be simultaneously inserted into the opposing tissues of an incision. This requires that a physician use one hand to approximate both opposing tissues of an incision and another hand to simultaneously insert the tines of the staple into the respective opposing sides. This can be particularly limiting during endoscopic procedures in which the physician needs one hand to operate the endoscope. Moreover, since both tines enter the opposing sides of the tissue simultaneously, the tines cannot be used to gather and approximate the opposing tissues. Accordingly, there is a need for a stapler and an SMA staple that resolves or improves upon any of these drawbacks.